Frost measuring device



July l5, 1941. E. J. FIELDS FROST MEASURING DEVICE Filed Jan; 17, 1939 mgl.

Inventor. Ernest J Fields,

b Wwf/CWM.

y His Attorney Patented July 1s, 1941 rnos'r MEAsUiuNG DEVICE Ernest J. Fields, E rie,

. Electric Company,

Pa., assignor to General a corporation of New York Application January 17, 1939, Serial No. 251,341

8 Claims'.

My invention relates to refrigeration particularly to means for measuring. the accumulationof frost on the surface associated with mechanical r tus.

It is generally known that the excessive accumulation of frost'or ice Aon the cooling unit or evaporator of a mechanical refrigerator decreases efrigerating apparaand more of the cooling unit I the eiciency of refrigeration. customarily, the

purchaser of a mechanical refrigerator of the y domestic type is informed bythe vendor or by means of printed instructions of the necessity of defrosting the cooling unit at intervalsaccording to the rapidity and amount of frost accumulation. However, it is impossible for the user of the refrigerator to correctly determine the proper time for defrosting merely by glancing at the cooling unit so that frequently the equipment is `operated at low efficiency with the consequent higher cost due to the heavy consumption of electric energy.

`Accordingly, it is an object of -my invention to provide a new and improved means for measuring the accumulation of frost on the cooling unit of a mechanical refrigerator which is simple, rugged and inexpensive to manufacture.

Further objects and advantages of my invention will become apparent as the'following de- I 'scription proceeds and the features ofl novelty which characterize-my invention will be pointed out with particularity -in the claims annexed to and forming a part of this specification.

For a better understanding of my invention supported in relatively poor thermal exchange l relationship with the evaporator as on the cooling unit by a second member or support I4 of relatively low heat conductivity characteristics.

In use theoperator need only glance at Athe terminal member |3a. of measuring device I3. As will be seen by reference to Fig. 4,- when the frost or ice layer` builds out even with the member 3a, that is, to the position indicated by the numeral I6, the in the depression between adjacent ridges of ice 3| and concealed .to an observ `the surface of the unit adjacent to and in the vicinity of the member |3a or along thetops of the ridges 3| of the ice layer I6, if the measuring device' takes the form shown in the drawing, thereby apprising the operator or user ofthe necessity for defrosting the cooling unit In the modification illustratedrin Figs. 5 and 6 a frost measuring device 33 of relatively low heat conducting material is shown as projecting outwardly from the cooling unit With this arrangement the frost gradually builds outwardly along the frost measuring device 33 to the predetermined thickness at which point the frost layer conceals the measuring device 33, as previously described. ,y

With reference to Fig. 1, the refrigerator Ill reference may be had to the accompanying drawv ing in which Fig. 1 is a fragmentary view of a refrigerator embodying my invention;4 Fig. 2 is an enlarged perspective view of a portion ofthe cooling unit shown in Fig. 1 illustrating the application of my invention; Fig. 3 is a view, partly in section, of a portion of the cooling unit and frost measuring device shown in Fig. ltaken along the line 3 3 of Fig. 2; Fig. 4- is a schematicview, partly in section, illustrating the operation of the frostmeasuring device shown in Fig. 1; Fig. 5 is a modication of the frost indicating means illustratedin Figs. 1 to 4; ly in section, of the modification shown in Fig. 5 taken along the line 6 6 of Fig. 5.

and Fig. 6 is a view, part- In the embodiment of my invention illustrated" Afrostopening. in the front wall in order to provide access to the food compartment |2, the opening being closed by a door |8. Shelves I9 are prof vided for more convenient storage of articles placed within the refrigerator. A temperature control switch 20' of lany suitable type is illustrated on the front of the cooling unit in order to permit adjustment of the operating temperature within the compartment |2 and also to permit defrosting of the cooling unit. The freezing compartment within the `cooling unit is closed by meansv of a door 2|. Any suitable refrigerating system may be employed. I have shown in Fig. 2 a temperature control bulb 22 .for determining the period-of operation of the refrigerating machinery in a manner well understood in the art. Any suitable means may be utilized to maintain the control bulb 22 in good thermal contact with the surface of the cooling- Yunit I have illustrated the use of acontrol bulb clamp 23 suitably secured to the cooling unit as by means of screws 24 threadingly engaging suitable threaded apertures in a suitable bracket 25. Bracket 25l may be secured to the cooling unit in any suitable fashion as by welding, for example. .l

member |3a will be situated er sighting along ducted between member Ila and evaporator example, in order Figs. 2 and 3 thefrost measuring device Il accumulation of ice device I3 illustrated in Figs. 1 to 4, the member Ila is shown as substantially cylindrical in shape and suitablysupported from the clamp 2l by means of a support member Il. 'I'he support Il, illustrated as a wire in the drawing, should be made from a material of low heat conductivity in order to minimize the conduction of heat between the evaporator or cooling unit I I and the terminal member Ita. Stainless steel has proved very satisfactory for the member Il and may be secured to clamp 23 in any suitable manner as by welding. The terminal member Ila may be formed of any desired material. I prefer to use a material which is relatively non-heat conductive because the support member Il may then be relatively short in length whereas if member Ila is relatively heat conductive, the low heat conductive support must be long enough to prevent any' substantial between member Ida and cooling unit II. A molded plastic such as rubber or a molded phenolic or urea resin is satisfactory although other suitable materials will readily occur to those skilled in the art. It will be understood, however, that at least a portion of the measuring device must be made of a relatively non-heat conductive material. For instance, if both terminal member I3a and support Il are made from metal which is relatively heat conductive. as aluminum, for example, the measuring device will begin to coat over with frostas soon as the cooling unit begins to frost over and the ice accumulation will build up as rapidly on the measuring device as on the cooling unit. If, however, the support Il is relatively non-heat' conductive, the heat con- In the measuring minimized and member Ila will not readily coat over with frost. In order to make the member I3a more readily visible to the user, I have found it desirable to color the member Ila as red, for to provide a contrast to the whitebackground of the frost accumulation.

The evaporator'or cooling unit II is illustrated as comprising a fiat plate 26 and an outer cor;` rugated plate 21 suitably secured thereto as b welding in order to provide passages refrigerant circulated therein. Asbest shown in be placed-between the user of the refrigerator may sight along transference of heat Ilis4 28 for the Y \spaced a predetermined two corrugations' 20 so t a e` exchange relationship outer wall 3l of the cooling unit and when thebuilds out to the thickness represented by dotted ample, the frost measuring device I3 will be hidden in the depressionor valley portion between the ridges 3| of the frost accumulation and the necessity for defrosting is determined.

It willbe apparent thatthe frost measuring device Il need not necessarily be placed between corrugations 29 but such arrangement is desirable because, when so placed, the indicating device I3 projects a minimum distance into the foodspace ofthe refrigerator Il and is therefore less from articles being moved within subject to blows the compartment Il.-

I have found that an accumulation of frost to a thickness of approximately maybe permitted without appreciably affecting the efficiency of refrigeration. Therefore, in the first described embodiment of my invention the side of, member i3d which is farthest from the coolingunit II should be' spaced that distance from the cooling unit Il.

Figs. 5 and 6 illustrate a modification of my invention in which the measuring portion or75 ycooling unit line IC of the Fig. 4, for ex- \,and means te determine the wall of the cooling unit \,will conceal said member from 1 ried by said first heat conductivity conductivity characteristics. For example, a

molded plastic. as rubber or a molded phenolic or urea resin, is satisfactory. with this arrangement, the extending portion on the cooling `unit mentioned limits.

Other modifications will readily occur to those skilled in the Por instance, the measuring device Il may be of any shape. may be secured within the cabinet in any desired fashion and may be located in .any desired place so long as the measuring device is positioned proximate a of the thickness of the ice accumulation.

While I have shown and described particular embodiments of my invention, I do not desire my invention to be limited to the particular constructions shown and described and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

what I claim as new and desire'to secure by Letters Patent of the United States is:

i. In a mechanical refrigerator, a cooling unit,

and a frost measuring device so arranged with respect to said cooling unit that an accumulation of frost on said unit of predetermined thickness will conceal said device from the view of the user sighting along the surface of said unit associated with said device whereby the user is apprised of the need for defrosting said unit, at least a portion of said device having relatively low heat conin order-to minimize. the

ductivity characteristics n accumulation of lfrost on said measuring device. ,2. Irranisnechanical refrigerator, a cooling unit, and mea for determining the need fordefrosting said unit, said means comprising a member distance from said cooling unit and in relatively poor thermal with said unit, said member being positioned so a predetermined thickness of frost onsaid unit Y the view of an \observer sighting along the surface A.of the unit associated with said device.

\ 3. In a mechanical refrigerator, y need for defrosting `\said unit,fsaid means including a first member. in heat exchange relationship with and supported on 'said lcooling ing formed of a material having relatively\low characteristics, and said second member being spaced a predetermined distance from said cooling unit whereby said second meml ber will be concealed from an observer facing the front of said unit and sighting along the surface thereof on which said determining means is supported when the frost accumulation on said cool-V ing coil -builds outwardly to a predetermined thickness. Y f

4. In a mechanical refrigerator, a cooling unit having a corrugated exterior surface, and a device spaced a predetermined distance -from said and arranged between adjacent cor- 'device Il extends outwardly from ,any suitable fashion but p Ilshouldbeofsiich v so that it is indicative that the accumulation ofa cooling unit,

unit, and a second member car'l member, said first member berugations of said unit whereby an accumulation of frost of a predetermined thickness onsaid corrugations will conceal said device from an observer sighting across the ice accumulated on the corrugations in the vicinity of said device, thereby determining the need for defrosting said unit, at least a portion of said device having relatively low heat conductivity characteristics in order to minimize the accumulation of frost on said device.

5. In a mechanical refrigerator, a cooling unit having a corrugated exterior surface, and means to determine the need for defrosting said unit, said means including a rst member in heat exchange relationship with and supported on said cooling unit and being formed of a material having relatively low heat conductivity and a second member carried by said rst member, said members being arranged in the space between two adjacent corrugations and said second member being disposed a predetermined distance from said cooling unit whereby said second member will be visible to an observer sighting across the ice accumulated on the corrugations in the vicinity of said device until the frost accumulation on said cooling coil and corrugations builds out to and conceals said second member.

6. In a. mechanical refrigerator, a cooling unit, and means for determining the need for defrosting said unit comprising a member of relatively low heat conductivity material in heat exchange relationship with and supported by said unit and extending laterally therefrom whereby the accumulation of frost on said unit to a.4 predetermined thickness will conceal said member from the view of an observer facing the front of said unit and. sighting along the surface thereof on which said determining means is supported.

7. In a mechanical refrigerator, a cooling unit, and means for determining the need for defrosting said unit comprising a member positioned proximate a wall of said unit, a portion of said member being disposed a predetermined distance from said unit whereby the user is apprised of the need for defrosting said unit when the accumulation of frost has built out approximately even with said portion as determined by anv observer sighting along the surface thereof in the vicinity ofsaid member, said portion being formed from a'material having relatively low heat conductivity characteristics in order that said portion will not readily accumulate frost thereon. `v

8. In a mechanical refrigerator, a cooling unit, and means for determining the need for defrosting said unit comprising a. member positioned proximate a wall of said unit, the edge of said member most remote from .said unit being disposed a predetermined distancefrom said unit whereby the user is apprised of the need for defrosting said unit when the accumulation of frost has built out approximately even with said edge as determined by an observer facing the front of the unit and sighting along the surface thereof, that portion of said member adjacent said edge being formed from a material having relatively low heat conductivity characteristics in order that said portion will not readily accumulate frost thereon.

ERNEST J. FIELDS. 

